Prilagodba na uvjete liofilizacije i antioksidacijski potencijal Levilactobacillus brevis sojeva

undergraduate thesis

• Title (english): Adaptation to lyophilization conditions and antioxidant potential of Levilactobacillus brevis strains
• Author: Petra Martinović
• Mentor: Jasna Novak (mentor)
• Mentor: Katarina Butorac (pomoć pri izradi, neposredni voditelj)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Biochemical Engineering); (Laboratory for Antibiotic, Enzyme, Probiotic and Starter Cultures Technology); Zagreb
• Defense date and country: 2024-09-10, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

U ovom završnom radu analizirani su bakterijski sojevi Levilactobacillus brevis MB1, MB2, MB13 i MB20, izolirani iz majčinog mlijeka s prethodno evaluiranim funkcionalnim svojstvima. Cilj ovog rada bio je ispitati lioprotektivna svojstva, nusproizvoda mliječne industrije, permeata, slatke i kisele sirutke, kao medija tijekom liofilizacije biomase L. brevis. Dodatno je provedena preliminarna analiza antioksidacijskog potencijala L. brevis sojeva. Temeljem rezultata ustanovljeno je da tri od četiri soja imaju tendenciju većeg postotka uklanjanja DPPH (2,2 difenil-1-pikrilhidrazil) radikala. Također, cilj je bio ustanoviti potencijalnu ulogu S-layer proteina, te usporediti sojeve L. brevis, prije i nakon ekstrakcije S-proteina, kako bi se odredila povezanost ovih proteina i zaštite stanične stijenke liofiliziranih stanica tijekom liofilizacije. SDS-PAGE (engl. Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresis) analizom potvrđena je prisutnost S-layer proteina u sojevima L. brevis. Analiza je pokazala da kada L. brevis eksprimiraju gene koji kodiraju za S-layer proteine iskazuju veću otpornost i prilagodbu na uvjete liofilizacije. Među analiziranim, soj L. brevis MB13, uz primjenu permeata kao lioprotektivnog medija, preživljava u najvišem broju bakterijskih stanica te s najmanjom razlikom u broju stanica prije i nakon liofilizacije, s vrijednošću Δlog(CFU/mL)=0,09 što potiče daljnja istraživanja ponovnog iskorištenja ovog nusproizvoda unutar aspekata održivosti.

Abstract (english)

In this final work, bacterial strains Levilactobacillus brevis MB1, MB2, MB13 and MB20, isolated from human milk, with previously evaluated functional properties, were analyzed. The aim of this work was to examine the lioprotective properties of dairy industry by-products, permeate, sweet and sour whey, as a medium during lyophilization of L. brevis biomass. In addition, a preliminary analysis of the antioxidant potential of L. brevis strains was performed. Based on the results, it was established that three of the four strains have a tendency to a higher percentage of DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) radical removal. Also, the goal was to establish the potential role of S-layer proteins, and to compare L. brevis strains before and after extraction with S-proteins, in order to determine the association of these proteins in the protection of the cell wall of lyophilized cells during lyophilization. SDS-PAGE (Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresis) analysis confirmed the presence of S-layer protein in L. brevis strains. The analysis showed that S-layer expressing L. brevis show greater resistance and adaptation to lyophilization conditions. Among those analyzed, strain L. brevis MB13, when the use of permeate as a lioprotective medium, survives in the highest number of bacterial cells and with the lowest difference in the number of cells before and after lyophilization, with a value of Δlog(CFU/mL)=0,09.

• Keywords: antioksidacijski potencijal; Levilactobacillus brevis; S-layer proteini; liofilizacija; permeat; sirutka
• Keywords (english): antioxidative potential; Levilactobacillus brevis; S-layer proteins; lyophilization; permeate; whey
• Language: croatian
• URN:NBN: urn:nbn:hr:159:108889
• Study programme: Title: Biotechnology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka biotehnologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka biotehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-09-23 10:28:23